Newmark Displacement Research Articles

A simplified method for estimating Newmark displacements of mountain reservoirs

In the present article we propose a new simplified method for assessing the seismic performance of large mountain reservoirs. The pseudo-empirical regression model is established on the basis of decoupled dynamic analyses performed on 7 accelerograms applied to 33 structural and geotechnical configurations. We study the influence of embankment geometries and mechanical properties on the prediction of earthquake-induced permanent displacements estimated by Newmark analyses. We also discuss the relevance of our model by carrying out comparisons with existing simplified models and with post-seismic field observations on earth dams. A regression analysis using parameters of interest provides a pseudo-empirical predictive equation to carry out rapid, preliminary assessments of the seismic performance of mountain reservoirs.

An uncoupled procedure for performance assessment of slopes in seismic conditions

To assess the seismic performance of slopes, the simplified displacement-based methods represent a good-working balance between simplicity and reliability. The so-called uncoupled methods permit to account for the effects of deformability and ductility by computing separately the dynamic site response and the sliding block displacements. In this paper the procedure proposed by Bray and Rathje (1998) was revised and adapted to Italian seismicity on a set of subsoil models, representative of the different soil classes specified by the Italian and European Codes. The relationship expressing the decrease of the equivalent acceleration with earthquake/soil frequency ratio was then obtained by means of dynamic 1D seismic response analyses. Statistical correlations between calculated Newmark displacements, significant ground motion parameters and the critical acceleration ratio were also derived. To estimate the reference ground motion parameters necessary for the full implementation of the proposed procedure, literature predictive equations, calibrated on strong motion records of international databases, were revised for the Italian seismicity. These ground motion prediction equations, together with simplified displacements relationships, allowed for developing an original quick procedure to evaluate the seismic slope performance by specifying the probability of exceedance of a threshold displacement, based only on few seismic input motion parameters.

Erratum to: Newmark displacement model for landslides induced by the 2013 Ms 7.0 Lushan earthquake, China

The original version of this article unfortunately contained a mistake. The presentation of Fig. 1 was incorrect.

Seismic landslide hazard assessment in the Tianshui area, China, based on scenario earthquakes

This work represents a regional potential seismic landslide hazard assessment for the Tianshui area, southeastern Gansu Province, China. The peak ground accelerations for two specific seismic scenarios (Ms 7.0 and 8.0) are estimated through empirical attenuation relationships. They are then combined with the slope threshold accelerations to calculated cumulative displacements through the Newmark’s sliding rigid-block model. Potentially unstable areas are identified based on the predicted Newmark displacement. The results show that both of the scenarios are capable of producing widespread slope instabilities, mainly loess landslides in the near-fault region, and that the Ms 7.0 earthquake would induce more slope instabilities around Tianshui city. The high-risk zones are concentrated mainly in the loess or mudstone areas with slope greater than 30°, especially on the banks of the Wei River, Xi River, and Niutou River, and pose a threat to the Longhai Railway line and the surroundings of Tianshui city. The potential damage to traffic networks and to built-up areas in Tianshui city is also mapped. These maps represent a preliminary assessment that can be utilized by local government to define the seismic landslide hazard better for future detailed risk evaluation, emergency plans, and engineering design.

A one-step Newmark displacement model for probabilistic seismic slope displacement hazard analysis

Estimating the earthquake-induced sliding displacement is important in assessing the stability of slopes during earthquakes. Current Newmark displacement models generally use ground motion intensity measures (IMs) as predictors, and the uncertainties of predicting IM values need to be accounted for in probabilistic seismic slope displacement hazard analysis. This paper aims at developing a simple one-step predictive model for the Newmark displacement based on only four seismological parameters (moment magnitude, rupture distance, fault categories and shear wave velocity at top 30m Vs30) rather than any IMs. The predictive model is suitable for critical acceleration from 0.02g to 0.25g, covering most of the susceptible earthquake-induced landslide cases. First, the proposed one-step model is compared with some recently developed IM-based Newmark displacement models. It is found that both the median predictions and the variabilities of the proposed one-step model are in reasonable agreement with those obtained by the IM-based models. Second, several hypothetical slopes are used to compare the slope displacement hazard curves between the one-step model and the IM-based models. The new model can be used as an alternative method for a fully probabilistic analysis of the earthquake-induced slope displacements. In addition, spatial correlations of the Newmark displacement residuals are also investigated using strong-motion data from the Northridge and Chi-Chi earthquakes.

Occurrence probability assessment of earthquake-triggered landslides with Newmark displacement values and logistic regression: The Wenchuan earthquake, China

The Newmark displacement model has been used to predict earthquake-triggered landslides. Logistic regression (LR) is also a common landslide hazard assessment method. We combined the Newmark displacement model and LR and applied them to Wenchuan County and Beichuan County in China, which were affected by the Ms. 8.0 Wenchuan earthquake on May 12th, 2008, to develop a mechanism-based landslide occurrence probability model and improve the predictive accuracy. A total of 1904 landslide sites in Wenchuan County and 3800 random non-landslide sites were selected as the training dataset. We applied the Newmark model and obtained the distribution of permanent displacement (Dn) for a 30×30m grid. Four factors (Dn, topographic relief, and distances to drainages and roads) were used as independent variables for LR. Then, a combined model was obtained, with an AUC (area under the curve) value of 0.797 for Wenchuan County. A total of 617 landslide sites and non-landslide sites in Beichuan County were used as a validation dataset with AUC=0.753. The proposed method may also be applied to earthquake-induced landslides in other regions.

Assessment of Earthquake‐Induced Landslide Hazard in Greece: From Arias Intensity to Spatial Distribution of Slope Resistance Demand

Abstract The earthquake‐induced landslide hazard in Greece is evaluated by means of a parametric time probabilistic approach. First, by taking into account the characteristics of seismicity affecting Greece, we calculated occurrence probabilities for different levels of seismic shaking expressed in terms of Arias intensity for a time interval of 50 yrs. Then, by utilizing the linkage of Newmark displacement with Arias intensity and critical acceleration, we mapped the spatial distribution of the slope strength demand that imply a 10% probability that displacement will exceed critical thresholds for potential seismic triggering of incoherent and coherent landslides. The obtained results suggest that the areas of western Greece and the broader region of the Gulf of Corinth are the most exposed to conditions of seismic triggering of both kinds of landslides. The derived slope strength demand maps could provide the basis for the assessment of whether particular slopes have a significant failure probability by comparing the estimated strength demand with the actual critical acceleration values calculated from slope material properties and slope angle. We exemplified this approach at a coastal area of the western Gulf of Corinth, where, by considering situations expected in dry and wet periods, we also demonstrated that earthquake effects on slope stability depend on the season of earthquake occurrence.

Newmark displacement model for landslides induced by the 2013 Ms 7.0 Lushan earthquake, China

Predicting approximate earthquake-induced landslide displacements is helpful for assessing earthquake hazards and designing slopes to withstand future earthquake shaking. In this work, the basic methodology outlined by Jibson (1993) is applied to derive the Newmark displacement of landslides based on strong ground-motion recordings during the 2013 Lushan Ms 7.0 earthquake. By analyzing the relationships between Arias intensity, Newmark displacement, and critical acceleration of the Lushan earthquake, formulas of the Jibson93 and its modified models are shown to be applicable to the Lushan earthquake dataset. Different empirical equations with new fitting coefficients for estimating Newmark displacement are then developed for comparative analysis. The results indicate that a modified model has a better goodness of fit and a smaller estimation error for the Jibson93 formula. It indicates that the modified model may be more reasonable for the dataset of the Lushan earthquake. The analysis of results also suggests that a global equation is not ideally suited to directly estimate the Newmark displacements of landslides induced by one specific earthquake. Rather it is empirically better to perform a new multivariate regression analysis to derive new coefficients for the global equation using the dataset of the specific earthquake. The results presented in this paper can be applied to a future co-seismic landslide hazard assessment to inform reconstruction efforts in the area affected by the 2013 Lushan Ms 7.0 earthquake, and for future disaster prevention and mitigation.

Influence of strong motion characteristics on permanent displacement of slopes

Landslides triggered by moderate to major earthquakes are a recognized seismic hazard. Arias Intensity (I a) is a key intensity measure of the ground motion, but significant duration is widely used to define strong motion duration. We calculate Newmark’s displacements using earthquake records bracketing a broad range of Arias Intensity and significant duration employing Newmark’s rigid block method and a number of yield accelerations. Total landslide displacement increases with the increase in the energy content of the ground motion (I a) above a threshold. Such threshold may be expressed as a function of yield acceleration of the slope regardless of the ground motion characteristics. Newmark displacement decreases with increasing duration for earthquakes with similar energy content. The wide scatter in the results converges when using formal dimensional analysis. Self-similar symmetry may facilitate the assessment of the performance of slopes during earthquakes. The mathematical framework for probabilistic determination of landslides displacement may be a useful aid to estimate the likelihood of landslide hazards provided that the geotechnical properties of the slopes are known.

Predictive model of Arias intensity and Newmark displacement for regional scale evaluation of earthquake-induced landslide hazard in Greece

Defining the possible scenario of earthquake-induced landslides, Arias intensity is frequently used as a shaking parameter, being considered the most suitable for characterising earthquake impact, while Newmark׳s sliding-block model is widely used to predict the performance of natural slopes during earthquake shaking. In the present study we aim at providing tools for the assessment of the hazard related to earthquake-induced landslides at regional scale, by means of new empirical equations for the prediction of Arias intensity along with an empirical estimator of coseismic landslide displacements based on Newmark׳s model. The regression data, consisting of 205 strong motion recordings relative to 98 earthquakes, were subdivided into a training dataset, used to calculate equation parameters, and a validation dataset, used to compare the prediction performance among different possible functional forms and with equations derived from previous studies carried out for other regions using global and/or regional datasets. Equations predicting Arias intensities expected in Greece at known distances from seismic sources of defined magnitude proved to provide more accurate estimates if site condition and focal mechanism influence can be taken into account. Concerning the empirical estimator of Newmark displacements, we conducted rigorous Newmark analysis on 267 one-component records yielding a dataset containing 507 Newmark displacements, with the aim of developing a regression equation that is more suitable and effective for the seismotectonic environment of Greece and could be used for regional-scale seismic landslide hazard mapping. The regression analysis showed a noticeable higher goodness of fit of the proposed relations compared to formulas derived from worldwide data, suggesting a significant improvement of the empirical relation effectiveness from the use of a regionally-specific strong-motion dataset.

Incorporating Triggering and Environmental Factors in the Analysis of Earthquake-Induced Landslide Hazards

Pingwu County of Sichuan Province was severely hit by the 12 May 2008 Wenchuan Earthquake and experienced widely distributed earthquake-induced landslides. We proposed an integrated method that incorporates landslide triggering factors embedded in the Newmark displacement computation and other environmental factors, expressed as lithology, land-use type, vegetation cover (Normalized Difference Vegetation Index, NDVI), elevation, and profile and plan curvature, in the analysis of earthquake-induced landslide hazards in the study area. The earthquake-induced landslide inventory of this area was obtained by visual interpretation of two high-resolution SPOT-5 images before and after the earthquake. We used GIS tools to generate an equal number of landslide and non-landslide cell samples in a 30-m grid map, and assigned triggering and environmental variables to each cell. A logistic regression model was built to investigate the occurrence of earthquake-induced landslides. The results show that Newmark displacement (in which triggering factors are embedded) and lithology (as an environmental factor) were the two dominant variables controlling landslide occurrence. Other environmental factors, including NDVI, land-use type, and elevation, also significantly affected landslide occurrences. Overall 81.2 % correctness was achieved in the regression model. The results confirm the predictive power of our method, which integrates both triggering and environmental factors in modeling earthquake-induced landslides.

지진시 산사태 발생 예측 및 산지 내 문화재 영향 분석

문화재가 위치하고 있는 서울특별시 종로구 일대의 산지를 연구지역으로 선정하고 Newmark displacement model을 이용하여 지진으로 유발되는 산사태 위험지 변화와 산사태로 인한 토석류 흐름 양상을 예측하여 연구 지역에 분포하고 있는 문화재에 미치는 영향을 분석하였다. 연구 결과, 지진으로 유발되는 산사태 발생 위험지에는 문화재가 위치하지는 않는 것으로 분석되었으나, 토석류 예상 이동경로 상에 사직단이 위치하고 있어 이에 대한 추가 연구가 필요할 것으로 사료된다. It was selected as the study area where heritage are located on the Mountain in Seoul. The variation of landslide risk induced earthquake by using the Newmark displacement model and the prediction of debris flow pattern due to landslides were performed. And these effects on heritage distributed in the study area were investigated. As a result, it was analyzed that heritage on landslide risk areas induced earthquake does not be placed, however the further research for Sajikdan on the predicted moving path of debris flow would be recommendable.

Effect of the acceleration component normal to the sliding surface on earthquake-induced landslide triggering

In 2008, the Wenchuan Mw 7.9 earthquake triggered a large number of landslides in the Longmenshan area. Among them, the Donghekou landslide is a gigantic one, which buried four villages and one elementary school. During the Wenchuan earthquake, large accelerations, especially vertical, were produced, which should to be taken into account in the dynamic analysis of slope stability. However, the vertical acceleration, which can largely influence the acceleration component normal to the sliding surface, is often overlooked in dynamic analysis of slope stability. In this work, the initiation of the Donghekou landslide is analyzed by using Newmark’s sliding block model. Comparative analyses of conditions both with and without an acceleration component normal to the sliding surface, which is contributed mainly by the vertical acceleration, are then conducted to investigate its role in triggering the Donghekou landslide. Research results show that the initiating time of the Donghekou landslide would be earlier considering the acceleration component normal to the slide surface than without it due to larger estimated Newmark displacement. This conclusion is then verified by simulated results on the basis of DEM. It means that initiation of landslides can be influenced significantly by seismic acceleration component normal to sliding surface, especially in the area with large vertical acceleration.

GIS application for regional assessment of seismically induced slope failures in the Sierra Nevada Range, South Spain, along the Padul Fault

Complete rupture of the Padul Fault represents one of the largest plausible earthquakes in the Sierra Nevada Range, one of the most seismically active regions of Spain. We performed a regional assessment of earthquake-triggered slope instabilities in the western part of the range to determine the most likely types of failures from such an earthquake in the region and suggest where such failures have a higher likelihood of occurring. These results are broadly useful for management of regional life-lines and future development. First, a slope-instability inventory of the Sierra Nevada was produced to identify the most common instability types. Subsequently, the Newmark’s sliding rigid-block methodology, implemented in a geographic information system, was used to obtain the distribution of Newmark displacements in the area considering a M w 6.6 earthquake on the Padul Fault. The Newmark displacements were then compared to the distribution of the inventoried slope instabilities to identify the areas where seismicity could reactivate old slope instabilities or generate new ones, and to identify the involved landslide typology. The most likely seismically induced slope instabilities in the Sierra Nevada are rock falls and rock slides. These types of instabilities could be triggered by Newmark displacements of 2 cm or less.

Slope instabilities triggered by the 11th May 2011 Lorca earthquake (Murcia, Spain): comparison to previous hazard assessments and proposition of a new hazard map and probability of failure equation

The Lorca Basin has been the object of recent research aimed at studying the phenomena of earthquake-induced landslides and its assessment in the frame of different seismic scenarios. However, it has not been until the 11th May 2011 Lorca earthquakes when it has been possible to conduct a systematic approach to the problem. In this paper we present an inventory of slope instabilities triggered by the Lorca earthquakes which comprises more than 100 cases, mainly rock and soil falls of small size (1–100 $$\hbox {m}^{3}$$ ). The distribution of these instabilities is here compared to two different earthquake-triggered landslide hazard maps: one considering the occurrence of the most probable earthquake for a 475-years return period in the Lorca Basin $$(\hbox {M}_{\mathrm{w}}=5.0)$$ based on both low- and high-resolution digital elevation model (DEM); and a second one matching the occurrence of the $$\hbox {M}_{\mathrm{w}}=5.2$$ 2011 Lorca earthquake, which was performed using the higher resolution DEM. The most frequent Newmark displacements related to the slope failures triggered by the 2011 Lorca earthquakes are lower than 2 cm in both the hazard scenarios considered. Additionally, the predicted Newmark displacements were correlated to the inventory of slope instabilities to develop a probability of failure equation. The fit seems to be very good since most of the mapped slope failures are located on the higher probability areas. The probability of slope failure in the Lorca Basin for a seismic event similar to the $$\hbox {M}_{\mathrm{w}}$$ 5.2 2011 Lorca earthquake can be considered as very low (0–4 %).

산사면의 지진동 증폭 특성

지진 시 산사면의 안전성은 일반적으로 유사정적해석법이나 Newmark 변위법으로 평가된다. 두가지 방법에서 모두 사면에서의 최대가속도를 정의해야 하며 이는 설계기준에 제시된 지진계수를 이용하여 산정한다. 하지만 지진계수는 수평지반 지표면에서의 최대응답을 나타내므로 사면에는 원칙적으로 적용 가능하지 않다. 본 연구에서는 산사면에서의 증폭계수를 도출하기 위하여 다양한 두께와 전단파속도의 산사면에 대한 일련의 2차원 유사정적해석과 동적해석을 수행하였다. 산사면의 증폭계수는 수평지반과는 다르게 지표면에서의 응답을 적용하는 것이 아니라 시간이력에 따라 사면 파괴토체 내부에서 발생하는 모든 가속도합의 최대값과 암반노두에서의 최대지반가속도의 비율로서 계산하는 방법을 새롭게 적용하였다. 이와 같이 계산된 증폭계수는 평균값이 1에 가까우며 사면토체의 평균가속도는 크게 증폭되지 않는 것으로 나타났다. 경사가 30o인 산사면의 증폭계수는 수평지반의 계수에 비해서 14-50% 작은 것으로 나타났다. 이는 사면의 정상부 및 지표면 부근에서는 크게 증폭이 되지만 하부경계면에서는 증폭이 작아서 평균을 계산하였을 경우 작아지기 때문이다. 결론적으로, 수평지반에 대해서 제시된 증폭계수를 산사면에 적용할 경우, 증폭을 크게 과대예측할 수 있으므로 본 연구에서 제시된 증폭계수를 사용하는 것이 보다 합리적일 것으로 판단된다. Seismic stability of slopes is most often assessed through pseudo-static analysis or Newmark displacement method. In both types of analyses, it is necessary to define the maximum acceleration of the slope. It is current practice to determine the acceleration using the seismic site coefficients. However, the site coefficients are not compatible with slopes, since they were developed for horizontally layered soil profiles. In this study, a series of pseudo-static and dynamic analyses are performed on various mountain slopes, from which the amplification factors are derived. A new method for calculating the amplification factors is proposed in this study. In a slope, the ground acceleration varies in both the vertical and horizontal directions. In the proposed procedure, the calculated accelerations at each node inside the slope failure mass are summed. The amplification factor is defined as the ratio of the average acceleration of the soil mass to the rock outcrop peak acceleration. The factors calculated using the proposed method is shown to be close to 1 for mountain slopes modeled in this study. The factors are approximately 14-50% lower than coefficients developed for horizontal soil deposits. The derived factors are lower because even though the amplification at the slope crest is high, as well as on the surface of the slope, the amplification is low near the bottom of the soil layer. In summary, it is demonstrated that the use of the site coefficients derived for horizontally layered soil profile will lead to significant conservative estimate of the slope stability.

A time probabilistic approach to seismic landslide hazard estimates in Iran

Understanding where seismically induced landslides are most likely to occur is crucial in land use planning and civil protection actions aimed at reducing property damage and loss of life in future earthquakes. For this purpose an approach proposed by Del Gaudio et al. [1] has been applied to the whole Iranian territory to provide the basis to assess location and temporal recurrence of conditions of seismic activation of slope failures, according to the Newmark's model [2]. Following this approach, occurrence probabilities for different levels of seismic shaking in a time interval of interest (50 years) were first obtained through a standard hazard estimate procedure. Then, empirical formulae in the form proposed by Jibson et al. [3] and calibrated for the main seismogenic Iranian regions were used to evaluate the slope critical acceleration (Ac)x for which a prefixed probability exists that, under seismic shakings, Newmark's displacement DN exceeds a threshold×corresponding to landslide triggering conditions. The obtained (Ac)x values represent the minimum slope resistance required to limit the probability of landslide seismic triggering within the prefixed value. A map reporting the spatial distribution of these values gives comparative indications on regional different exposure of slopes to shaking capable of inducing failures and provides a reference for hazard estimate at local scale. The obtained results show that the exposure to landslide seismic induction is maximum in the Alborz Mountains region, where critical accelerations up to ∼0.1g are required to limit the probability of seismic triggering of coherent type landslides within 10% in 50 years.

Analysis of landslide damage caused by the 2008 Wenchuan earthquake using strong motion data: A case study in the Beichuan county town

The county town of Beichuan county, China, experienced catastrophic destruction due to landslides induce by the 2008 Wenchuan earthquake. In consideration of the special location of the county town, this paper selected the landslides induced in the town as representative of large-scale near-rupture landslides, and quantitatively analyzed why the landslide damage was so destructive in the town by using strong motion data obtained from the Wenchuan earthquake in the Longmenshan area. Three methods were employed to estimate the landslide damage using strong motion data. (1) Peak ground accelerations (PGAs) on the hanging wall were used to evaluate the PGAs on the landslide sites in the town. The evaluated average PGAs were all greater than 1 g, indicating that the ground motion intensity was very strong during the earthquake. (2) Acceleration time histories, from another station with similar geological conditions to the town, were used to evaluate the critical acceleration changing range, and the estimated values showed the geological conditions were very susceptible to earthquakes. (3) Acceleration time histories, from two stations on the hanging and foot walls of the rupture, and near the town, were used to calculate the Newmark displacements, and all the evaluated displacements indicated that landslides were very likely. The results show that the slopes, susceptible to earthquakes in the Beichuan county town, were easily triggered under such strong ground-motion intensity and developed into large-scale catastrophic events.

A method for predicting co-seismic displacements of slopes for landslide hazard zonation

Landslide hazard zonation based on co-seismic slope displacements has been applied in many regions. As there are a large number of slopes to be analyzed and it is impossible to obtain actual acceleration time histories for each of these slopes, the co-seismic displacements are often estimated by some simple empirical formulas, which are derived through regression analysis based on a certain set of acceleration time histories and can only be validly applied to regions similar to where the time history data were recorded. In this paper, treating the ground motion as a random process, a formula for calculating the expected value of Newmark displacement with the acceleration amplitude spectrum as input is derived. Since the formula is theoretically equivalent to the double integration procedure in a rigorous Newmark analysis, which has also been verified by careful comparisons of the calculated results, it can be applied for different regions. By combining the formula with ground motion simulations, a new method for estimating co-seismic slope displacements is proposed. The application of the method in the seriously struck area by Wenchuan earthquake shows that it is an effective tool for predicting co-seismic slope displacements as the predicted landslide distribution by using its estimated results agrees reasonably with the actual observations.

Different Dynamic Behavior of Potentially Sliding Blocks in Near and Far Field Earthquakes

Worldwide experience repeatedly shows that damages in different kind of slopes caused by earthquakes are highly dependent on site condition and epicentral distance. In this paper, a potentially sliding slope in Alborz region was selected as an example to investigate these two effects. In order to verify the analysis software, a hemicycle valley was first modeled and its amplification response to the Ricker wavelet was compared with the results of previous studies. The numerical model of the well-known Shafarood landslide located in the Reservoir of Shafarood dam was prepared and dynamic analysis of the model was performed. Eight far and near field acceleration time histories of different earthquakes in Iran was selected as input motion. Then, the average acceleration time history of the sliding block to each input excitation was calculated and the permanent Newmark displacement was evaluated using MATLAB software. The results demonstrate that the permanent displacement of the potentially sliding block in near field earthquakes is less than that for far field ones. Besides, it was concluded that the frequency content of the records has more influence on the Newmark displacement than the epicenter distance.